Cylinder 1 and 2 pistons were bad and starting to break off, 3&4 were still good. The other picture is a stock piston w/conn rod. These are Arias pistons. They think it ran lean.

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I've seen worse. How much boost you running? What engine management? How was the a/f ratio? Ignition timing?

 

Those aren't forged pistons, are they?

 

nevermind, just read they are arias.

Ouch! Now would you recommend those pistons? Or did they crap out on you out of nowhere?

 

I think this happen sometime during the break in period when i had the stock injectors in. I was running lean for the first 500 miles. That was back in march 05'. And it just got worst as I drove it. I was running 12 lbs of boost with a Aem Ems.

I tried not to boost while break in the motor. Then I installed some 550cc RC injectors but it may have been to late.

 

No Arias piston are good I just brought 4 new ones. They did hold up all this time.

 

what injectors were you running before the 550's? also did you have them custom make for your engine? cause the closest one is obviously going to be what they listed for the f22a1, but that engine only has a 95mm stroke vs the 97mm that the f23 has.....

 

I was running the stock injector 270cc (i think). Yes they were custom made, stock is 86mm I had 87mm. When i went back to buy the second set they said it would be 3 to 4 1/2 week to make, but they have 87.5mm off the self piston, and if I had the machine shop bore the cylinder walls out .5mm more I could pick them up today.
The price difference was $570 off the self and $650 custom

 

You had to have had some detonation in there. Did you ever hear the motor pinging?

 

I'd probably agree with the lean issue.... It looks similar to what snowcats/ATV pistons look like after it's been run lean...